Q: Can I shutdown my Iphone 6s if someone else is logged in with his password and ID?

Ihbinnoname wrote:

 

Can I shutdown my Iphone 6s if someone else is logged in with his password and ID?

Turn off your phone yes, you can do that.

why you have someone logged into your phone is another question.

Ihbinnoname wrote:

 

Yeah, that is a real question. Well I borrowed my phone to someone, and he refuses to give it back and he logged in with his password. So there is nothing I can do, at least to permanently shutdown that phone?

Well you made no mention of that person physically having your phone in your original post.

No you can't shut it down, you can probably restore it when you log into icloud.com and use the restore button.  But you will lose all of your data doing that.

If you had "Find My Phone" enabled on it you might be able to set it to lost mode (from any web enabled device)  and lock him out:

iCloud: Use Lost Mode

Find My iPhone: Lost Mode

Find My iPhone Activation Lock - Apple Support

Contact the police to report that your phone is stolen. Hope you know who the "someone" is that you lent it to.